Tableau Desktop and Tableau Server both support two different types of interactions with your data.
These include live connections and extracts.
This operation is controlled by the selector on the top right of your data source interface window.
Note that if you're using Tableau public, you won't have this option because everything defaults to
an extract.
If you're using the full version of Tableau desktop, you'll see that you have both options available
to you.
Live connections will keep a connection to the data source and we'll query the database or file.
Whenever a visualization is created, your sheet is filtered or otherwise modified on desktop or server.
Extracts will pull data from the source and extract it out into a tableau.
Proprietary hyper file format extracts can be scheduled on Tablo server to keep the data fresh, while
not adversely impacting the source platforms with queries.
Note that automatic refreshes either require Tablo server or Tableau online.
It's likely that your company or organization will need to utilize both live connections and extracts
for various use cases and scenarios.
Let's look at a few options as to why you would use extracts over live connections.
First, extracts can improve performance, especially for poorly performing database sources.
Extricates can also enable additional functionality.
This includes additional features that may be limited with live connections.
Specific database connections may have limitations on deep conversions, field operations and more.
Extracts also allow you to work with the data offline.
You won't need to work with a live connection to a database, and you won't need to be on a specific
network to utilize extracts.
Extracts also support very large datasets into the billions of records.
Finally, extracts are fast to create with the new high profile format.
Pulling data out of your systems is quick and easy.
One note regarding your data connection type is that when you're joining tables together, they'll need
to be the same type, either extract or live so you won't be able to join together and extracted local
file with a live database.
They'll both need to be the same type to be joined together.
In our next lesson, we'll look through the different customization options for extracts.